84 ESS A YS. 



the ordinary accidents that trees are heir to, and thus attain a 

 longevity far transcending the habitual duration of the spe- 

 cies. Is this view sustained by observation ? 



Before adducing the evidence which bears upon this ques- 

 tion, it is necessary to inquire how the actual age of a tree 

 may be ascertained. In most cases, — in all those trees which 

 increase in diameter by annual concentric layers, — that is to 

 say in nearly all trees except Palms and their allies, which for 

 the present we may leave out of the question, the age may be 

 directly ascertained by counting the annual rings on a cross 

 section of the trunk. The record is sometimes illegible or 

 nearly so, but it is perfectly authentic ; and when fairly de- 

 ciphered, we may rely on its correctness. 1 But the venerable 

 trunks, whose ages we are most interested in determining, are 

 rarely sound to the centre ; and if they were, even the para- 

 mount interests of science would seldom excuse the arboricide. 

 This decisive test, therefore, can seldom be practically em- 

 ployed, except in the case of comparatively young trees. The 

 most remarkable recorded instance of its application is that 

 of one of the old oaks at Bordza, in Samogitia (Russian Po- 

 land) ; which, having been greatly injured by a conflagration, 

 was felled in the year 1812, and seven hundred and ten 

 concentric layers were distinctly counted on the transverse 



1 The discovery, or at least, the first explicit announcement of the now 

 familiar fact, that ordinary trees grow by annual layers, so that the rec- 

 ord of their age is inscribed upon the section of the trunk, is generally 

 attributed to Malpighi. But, probably, we should understand this cele- 

 brated anatomist as merely giving a formal statement of what was already 

 popularly known ; for so obvious a fact could scarcely have escaped no- 

 tice. Professor Adrien de Jussieu, the present representative of that il- 

 lustrious family, has, moreover, lately reproduced a passage in the " Voy- 

 age de Montaigne en Italie," written in the year 1581, nearly fifty 

 years before Malpighi was born, which proves this to have been the case. 

 " Uouvrier, homme ingenieux et fameux a /aire de beaux instruments de 

 Mathe'matique, m'enseinga que tous les arbres portent autant de cercles qu'ils 

 ont dure d'anndes, et me le fit voir dans tous ceux qu'il avoit dans sa boutique, 

 travaillant en bois. Et la par tie qui regard le septentrion est plus e'troite, 

 et a les cercles plus serres et plus denses que V autre." 



And now it appears that Leonardo da Vinci knew, and mentioned it — 

 as well as phyllotaxis. (MSS. note in Dr. Gray's handwriting.) 



